The invention relates to a tomographic apparatus for producing transverse layer images of a radiography subject comprising a radiation measuring arrangement which contains a radiation source which produces a beam of rays, penetrating the radiography subject, the cross sectional extent of the beam perpendicular to the layer plane being equal to the layer thickness, as well as containing a radiation receiver which determines the radiation intensity behind the subject, comprising a rotating device for the measuring arrangement for the purpose of penetrating the radiography subject by radiation from various directions, and comprising a measured value converter for the transformation of the signals supplied by the radiation receiver into a layer image in which, between the radiation source and the radiation receiver, two hollow cylinders of radiation-absorbing material are disposed having the same diameters and a common axis between which a gap for the passage of the x-ray beam is left open, the radiography subject being supported so that the layer to be examined is within the confines of the cylinders and aligned with the plane of the gap.
A tomographic apparatus of this type is described in the patent application No. P 28 50 675.4. The two hollow cylinders here effect a suppression of the stray radiation in the instance in which the radiation receiver is designed as a stationary detector ring as well as in the case in which the radiation receiver is rotated together with the radiation source for scanning of the radiography subject.